The present invention relates to image sensors and, more particularly, to image sensors with light guide structures.
Electronic devices such as cellular telephones are often provided with digital image sensors. A typical image sensor has an array of pixels each of which has a photosensitive element such as a photodiode. Image sensor pixel arrays may contain thousands or millions of pixels. To ensure satisfactory image quality, each pixel should convert image light into electrons efficiently with low cross-talk. These challenges have been partly addressed by incorporating light guide structures into conventional image sensor pixels. During fabrication, light guide openings are etched through the surface dielectric layers on an image sensor. These openings are then filled with material having an elevated index of refraction. Light guide structures that are formed in this way help to channel incoming light to the photosensitive elements of the pixels. However, image sensors with conventional light guide structures are sometimes prone to cross-talk and could benefit from improved conversion efficiencies.